<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>2.5</title>
</head>
<body>
    <script>
        function fun(){
            let n = 'a';
            if(true){
                let n = 'b';
            }
            console.log(n); //'a'
        }
        fun();
    </script>
</body>
</html>